Owl Calibration 2017

This ticket records the results from the Owl wavelength calibration in 2017. This is the first time this has been attempted and the scripts used are still experimental/ not yet reviewed, but a record is still very useful.

The process uses the raw data to calculate a transmission spectrum which is then compared to that measured by FSF instruments (a wiki page has been prepared in /users/rsg/arsf/scratch_space/wiki_text_DELETE_AFTER_BECOMES_LIVE/Owl_Wavelength_Calibration.docx).

This ticket also records the first attempt at comparing the radiometric stability of the Owl over a year, with a percentage difference plot included in the data quality report. The process is documented in: /users/rsg/arsf/scratch_space/wiki_text_DELETE_AFTER_BECOMES_LIVE/Owl_Radiometric_Calibration.docx

Given the difference between the 2 measurements the offset measurement is not conclusive.

Manual inspection of the peak values suggests that fityk is correctly identifying the peaks and that the algorithm is working properly, so the difference may just be due to the spectral resolution of the Owl (50 nm).

More measurements should be taken in future for comparison, but with such small values compared to the spectral resolution, the wavelength shift is not currently of major concern.

Discussed the radiometric comparison results with Chris (FSF) and decided to not include these in the data quality report. We should wait until we have established a repeatable method, where the distances between the Owl and the laboratory black body are tightly fixed. This should be achievable in the next calibration using the newly finalised (Apr 2017 calibration) calibration jig. Not using the calibration file results as we can't explain the pattern.

Looking at the differences in the Apr calibration (12th - 19th) using the calibration jig doesn't show a massive improvement. There are still differences between the different bands. Plots are stored: /users/rsg/arsf/arsf_data/2017/misc/Owl_post_BB_cal_Apr/Owl_Variation/Lab_BB_comparisons/apr_comparisons